Field
Embodiments of the disclosure relate generally to the field of certification of heat blankets and more particularly to use of a thermochromatic coating of chromatic probes applied to a witness sheet, operative surface of the heat blanket or vacuum bagging film with a vacuum bagging system test layup in which the heat blanket is brought to operating temperature and activated chromatic probes are viewed under ultraviolet illumination.
Background
Heat blankets are a critical part of composite repair process for aircraft and other systems employing composite skins and structures. Heat blankets are applied to the surface of a repair area to provide the heat needed to cure the resin system in pre-impregnated ply stack-ups. It is essential that the thermal properties of the heat blankets are controlled and consistent across the entire area of the blanket. To assure even and repeatable curing processes. To certify and monitor the performance of heat blankets, it is currently required that a thermal camera or pyrometer be used to take images of the heat blanket vacuum-bagged to a silicon pad, while the power is turned on to the blanket. Many blankets fail due to very small hot spots showing up in large view IR images, resulting in significant cost and time expenditure. To avoid failing the heat blankets, by these potentially erroneous thermal outliers, small (2″ by 2″) view images are taken and averaged to provide a reliable certification process. With either the IR camera or the pyrometer, moving and aiming the sensor to produce the necessary small view grid pattern is time consuming and labor intensive.
It is therefore desirable to provide a system and method for certification of heat blankets which alleviates the shortcomings of the existing methods.